SOLUTION: A consumer looking to buy a used red Miata car will call dealerships until she finds a dealership that carries the car. She estimates the probability that any independent dealershi

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Question 1206753: A consumer looking to buy a used red Miata car will call dealerships until she finds a dealership that carries the car. She estimates the probability that any independent dealership will have the car will be 28%. We are interested in the number of dealerships she must call.
On average, how many dealerships would we expect her to have to call until she finds one that has the car? (Round your answer to the nearest whole number.)
Find the probability that she must call at most 7 dealerships. (Round your answer to four decimal places.)
Find the probability that she must call 5 or 6 dealerships. (Round your answer to four decimal places.)
Answer by ikleyn(52813) About Me  (Show Source):
You can put this solution on YOUR website!
.
A consumer looking to buy a used red Miata car will call dealerships until she finds a dealership
that carries the car. She estimates the probability that any independent dealership will have the car
will be 28%. We are interested in the number of dealerships she must call.
(a) On average, how many dealerships would we expect her to have to call until she finds one
that has the car? (Round your answer to the nearest whole number.)
(b) Find the probability that she must call at most 7 dealerships. (Round your answer to four decimal places.)
(c) Find the probability that she must call 5 or 6 dealerships. (Round your answer to four decimal places.)
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(b)  P =  =

         0.28%2A%281%2B0.72%2B0.72%5E2%2B0.72%5E3%2B0.72%5E4%2B0.72%5E5%2B0.72%5E6%29 = 0.28%2A%28%280.72%5E7-1%29%2F%280.72-1%29%29 = 1-0.72%5E7 = 0.9000 (rounded).


(c)  P = %281-0.28%29%5E4%2A0.28 + %281-0.28%29%5E5%2A0.28 = use your calculator.

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Thus  (b)  and  (c)  are solved,  answered and explained.

I left  (a)  unanswered,  since you packed TOO many questions in one post.